B737-800 FLT CREW HAS A TCAS RA DURING ILS APCH TO MROC.

Narrative

WE WERE INBOUND ON THE ILS FOR RWY 7; CAPTURED ON THE LOC AND GS AND ZEROED OUT ON THE HUD; IN OTHER WORDS DEAD ON COURSE AND CLRED FOR THE APCH. AT APPROX 4600 FT AND DSNDING; MROC TWR ADVISED; 'ACR XXX YOU HAVE TFC ON THE LOC WBOUND AT 4000 FT.' SINCE WE WERE ON THE LOC (EBOUND) AND DSNDING ON THE APCH IT WAS OBVIOUS THIS WOULD NOT WORK. WE IMMEDIATELY LOOKED FOR TFC; DID NOT GET A VISUAL; BUT GOT A SNAPSHOT GLANCE ON THE NAV DISPLAY OF THE POS OF THE ACFT. I WAS IN THE 5 MI RANGE AND ACFT WAS OFF NOSE AND SLIGHTLY TO THE R. IMMEDIATELY WE RECEIVED THE TCAS ALERT AND WITHIN SECONDS A TCAS CLB WARNING. I COMMANDED PITCH UP AND FO WAS FLYING FOLLOWED THE FLT GUIDANCE PERFECTLY. WE WERE FULLY CONFIGURED FOR LNDG AND ONLY CLBED 200 FT. AS SOON AS ACFT PITCHED UP I SAW ACFT OUT COPLT WINDOW TURNING TO PASS BEHIND OUR ACFT. THE ESCAPE EVENT ONLY LASTED A FEW SECONDS. THE ACFT WAS A SINGLE ENG AND WAS WITHIN 200-300 YARDS HORIZONTALLY; WITH NO VERT SEPARATION UNTIL WE INITIATED ESCAPE PROC. SUPPLEMENTAL INFO FROM ACN 726375: AS SOON AS ACFT PITCHED UP; THE CAPT SAW THE ACFT. IT WAS A HIGH WING SINGLE-ENG PROP ACFT AND BANKING TOWARDS US. THERE WAS NO WAY HE COULD SEE US WITH THAT AMOUNT OF BANK. I ESTIMATE HE WAS NO MORE THAN A 100 YDS AWAY AS I COULD SEE SOME OF THE DETAILS ON HIS WING. THE ESCAPE EVENT ONLY LASTED A FEW SECONDS BEFORE RECOVERING TO LAND.